Abstract
The aim of this paper is to evaluate the cyclic interfacial strength by cyclic nanoindentation tests. The specimen used in this study is PET substrate/ITO coatings layered specimen. In this study mono cycle nanoindentation test and 10 cycle nanoindentation were conducted on each load, and these results were compared. From indentation load and displacement curves, we classified those results into 3 types (A-C). These three types relate the maximum loads. After the cyclic indentation, we observed the surface profile by the function of atomic force microscope. On Type A, the deviations were observed on the edge on indentations. On Type B, some elongates were observed in the indentations. In addition the number of elongates increased by repeating nanoindentation. These phenomena can be explained by simple models. In this study, two types of fracture modes are proposed. They are "subsidiary fracture mode" and "buckling mode". From the deviation of indentation load and displacement curve, we proposed the method to estimate the energy used for thin film delamination and the interfacial strength was evaluated. The results are good agreement with the interfacial strength evaluated by peel test.
